The shipment of food grains over long distances has become commonplace in the modern world, with a substantial trade activity taking place both across the country and overseas. Grains, such as corn, wheat, oats, soybeans, etc., are often handled many times during the shipment and storage process before they find their way to the ultimate consumer. The repeated handling of the grains during shipment and storage results in physical abrasion of the shells of the grain, with a significant percentage of the individual grains having their shells broken open. Such damage to the protective outer shell of the grain enhances the probability that the grain will be spoiled, moldy, or otherwise contaminated by the time it reaches the consumer.
Corn and other grains are graded at the time that they are first brought to market on several qualities including weight/density, moisture percentage, apparent mold growth or other damage, and proportion of grain having broken shells. For example, corn is regularly tested and graded to determine the amount of "broken corn and foreign material" (BCFM) contained in the corn, and the percentage found in such screening processes determines the grade of the corn; e.g., a two percent increase in the proportion of broken corn may reduce the corn grade from No. 1 corn to No. 3 corn. Naturally, the higher grade corn demands a higher price in the marketplace.
While the grade of the corn may be known by the purchaser at the time the purchase is made, if the corn is thereafter to be transported long distances, such as overseas, the handling and jostling that the grain takes during shipment may result in substantial breakage of the individual grains. As a result, the grain at the point of use may be of a substantially lower grade than it was at the point at which it was purchased.
It is known that not all varities of grain have the same resistance to breakage during handling. Thus, it is very desirable to be able to predict whether the particular grain being purchased is more or less susceptible to breakage during the handling process. A commercial breakage tester, manufactured by Fred Stein Laboratories, Inc., of Atchison, Kansas, has been used commercially to test the mechanical strength of corn and other grain. This tester agitates grains held in a stainless steel cup by a rotating blade. Rotary or centrifugal guns for impact testing of grains are also known although not presently used commercially. See "A Mechanical Damage Susceptibility Tester for Shelled Corn," Ramesh Sharda and Floyd L. Herum, American Society of Agricultural Engineers, 1977 Winter Meeting; "A Centrifugal Gun for Impaction Testing of Seeds," J. Robert Cooke and James W. Dickens, 1971 Transaction of the ASAE, pp. 147-155. The high cost of commercial testers and the amount of time required to test a batch of grain has hindered wide spread use of the testers. Difficulties have been encountered with both commercial and proposed grain breakage testers in obtaining repeatability of the test results for samples of grain taken from the same batch or load. The failure of a tester to yield repeatable results reduces the confidence in the tester's ability to predict a likely level of damage in a grain after it has been shipped. The difficulty of testing the grains for breakage reliably becomes particularly acute for very durable grains which may show very little breakage when subjected to conventional testing methods. However, under the stress of repeated handlings that occur in overseas shipment, a significant percentage of even such durable corn has been observed to break and deteriorate; and it has also been observed that different varieties or batches of the more durable kinds of corn show different levels of resistance to breakage during long distance shipment. Up to now, it has not been possible to reliably descriminate between the more durable varieties of corn in order to predict their expected damage levels resulting from long distance shipment.